I have a 2012 JKUR (87K miles) and a 2013 Ford Explorer (83K). I've replaced both rear brakes but not the front. I thought it just had to do with how I drive but maybe it is more common than I thought.
This looks like what happened to mine. The only pad that was down to the metal was the rear passenger inside pad, I had to replace my rotor too.
The outside of the passenger rotor was totally fine, there was still a 3/8 inch brake pad.